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arXiv 2024年

作者： Pols, Mike Brocks, Geert Calero, Sofía Tao, Shuxia Materials Simulation & Modelling Department of Applied Physics and Science Education Eindhoven University of Technology Eindhoven5600 MB Netherlands Computational Chemical Physics Faculty of Science and Technology MESA+ Institute for Nanotechnology University of Twente Enschede7500 AE Netherlands

With the use of chiral organic cations in two-dimensional metal halide perovskites, chirality can be induced in the metal halide layers, which results in semiconductors with intriguing chiral optical and spin-selective transport properties. The chiral properties strongly depend upon the temperature, despite the basic crystal symmetry not changing fundamentally. We identify a set of descriptors that characterize the chirality of metal halide perovskites such as MBA2PbI4, and study their temperature dependence using molecular dynamics simulations with on-the-fly machine-learning force fields obtained from density functional theory calculations. We find that, whereas the arrangement of organic cations remains chiral upon increasing the temperature, the inorganic framework loses this property more rapidly. We ascribe this to the breaking of hydrogen bonds that link the organic with the inorganic substructures, which leads to a loss of chirality transfer. Copyright © 2024, The Authors. All rights reserved.

关键词： Hydrogen bonds

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All-SiC Fiber-Optic Sensor Based on Direct Wafer Bonding for High Temperature Pressure Sensing

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Photonic Sensors 2022年第2期12卷 130-139页

作者： Ting LIANG Wangwang LI Cheng LEI Yongwei LI Zhiqiang LI Jijun XIONG Science and Technology on Electronic Test&Measurement Laboratory North University of ChinaTaiyuan 030051China Department of Physics Taiyuan Normal UniversityJinzhong 030619China Institute of Computational and Applied Physics Taiyuan Normal UniversityJinzhong 030619China

This paper presents an all-SiC fiber-optic Fabry-Perot(FP)pressure sensor based on the hydrophilic direct bonding technology for the applications in the harsh *** operating principle,fabrication,interface characteristics,and pressure response test of the proposed all-SiC pressure sensor are *** FP cavity is formed by hermetically direct bonding of two-layer SiC wafers,including a thinned SiC diaphragm and a SiC wafer with an etched *** light interference is used for the detection and demodulation of the sensor pressure *** results demonstrate the sensing capabilities for the pressure range up to 800 *** all-SiC structure without any intermediate layer can avoid the sensor failure caused by the thermal expansion coefficient mismatch and therefore has a great potential for pressure measurement in high temperature environments.

关键词： SiC pressure sensor optical-fiber high temperature direct bonding

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Differential and integral cross sections for the valence-shell excitations in D2O studied by fast electron impact

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Physical Review A 2022年第6期105卷 062817-062817页

作者： Zi-Ru Ma Shu-Xing Wang Yi-Geng Peng Jian-Hui Zhu Yuan-Chen Xu Xiao-Jiao Du Li-Han Wang Wei-Qing Xu Yong Wu Jian-Guo Wang Lin-Fan Zhu Department of Modern Physics University of Science and Technology of China Hefei Anhui 230026 China Department of Applied Physics Nanjing University of Science and Technology Nanjing 210094 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China Center for Transformative Science ShanghaiTech University Shanghai 201210 China HEDPS Center for Applied Physics and Technology and College of Engineering Peking University Beijing 100871 China

The experimental generalized oscillator strengths (GOSs) for the valence-shell excitations of heavy water in 6.50–12.17 eV are determined by fast electron scattering with an incident electron energy of 1500 eV and an energy resolution of 80 meV. The experimental data of the Ã1B1←X̃1A1 transition between H2O and D2O show significant discrepancies around the minimum, and further theoretical calculations with nuclear effects accounted are recommended. The comparisons of the present GOSs of Ã1B1←X̃1A1 and B̃1A1←X̃1A1 transitions in D2O with theoretical calculations within the first Born approximation and the second Born approximation indicate that the higher Born terms become prominent at large momentum transfers. In particular, the GOSs of the dipole-forbidden transition 1A2←X̃1A1 are extracted, benefiting from the present high-energy electron scattering, where most of electronic dipole-forbidden transitions are not involved. By extrapolating the GOSs to the zero momentum transfer, the optical oscillator strengths for the corresponding dipole-allowed transitions are determined, which provide an independent cross-check for previous optical measurements. Moreover, the integral Born cross sections are scaled to an accurate level with the aid of the binding energy–excitation energy–scaling method. The relevant experimental data in this work can supplement the molecular database with electron collision data involving heavy water.

关键词： Atomic & molecular collisions Electronic excitation & ionization Electronic transitions

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Enhanced thermoelectric properties of two-dimensional Janus ferromagnetic LaBrI with strain-induced valley degeneracy

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Physical Review B 2025年第15期111卷 155433-155433页

作者： Anuja Kumari Raman D. K. Tanu Choudhary Raju K. Biswas Abhinav Nag Santanu K. Maiti Jagdish Kumar Physics and Applied Mathematics Unit Indian Statistical Institute 203 Barrackpore Trunk Road Kolkata- 700 108 India Department of Computational Sciences Central University of Punjab Bathinda-151 401 India Department of Physics M S Ramaiah University of Applied Sciences Bengaluru-560 058 India Department of Physics North Eastern Regional Institute of Science and Technology Nirjuli Arunachal Pradesh-791 109 India Department of Physics GGDSD College Rajpur Palampur-176 061 India

Since the successful synthesis of the MoSSe monolayer, which violated the out-of-plane mirror symmetry of transition metal dichalcogenide monolayers, considerable and systematic research has been conducted on Janus monolayer materials. By systematically analyzing the LaBrI monolayer, we are able to learn more about the novel Janus material by focusing on the halogen family next to group VIA (S, Se, Te). The structural optimizations have been carried out using pseudopotential-based Quantum Espresso code. Computed structural parameters are in good agreement with literature reports. The optimized crystal structures are used for computing the effect of strain on electronic and thermoelectric properties. Dynamical stability predicts that this material can withstand up to 10% of tensile strain. Computed electronic structure reveals material to be indirect wide band-gap ferromagnet with magnetic moment 1 µB. With increase in the biaxial tensile strain the band gap decreases. Furthermore, the computed magnetothermoelectric properties predict high Seebeck coefficient ∼400 µV/K and low thermal conductivity of ∼0.93 W/m K in LaBrI, which results in a high ZT∼1.84 for 4% strain at 800 K. The present study supports the fact that tensile strain on ferromagnetic LaBrI material can further enhance TE properties, making it a promising material for TE applications at higher temperatures.

关键词： Tensile strain

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Parity effects in Rydberg-state excitation in intense laser fields

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Photonics Research 2024年第12期12卷 3033-3039页

作者： YANG LIU XIAOPENG YI QI CHEN TIAN SUN HANG LV SHILIN HU WILHELM BECKER HAIFENG XU JING CHEN Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Institute of Applied Physics and Computational Mathematics Beijing 100088China Research Center for Advanced Optics and Photoelectronics Department of PhysicsCollege of ScienceShantou UniversityShantou 515063China Key Laboratory of Intelligent Manufacturing Technology of MOE Shantou UniversityShantou 515063China Max-Born-Institut 12489 BerlinGermany Hefei National Laboratory Department of Modern PhysicsUniversity of Science and Technology of ChinaHefei 230026China Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology Center for Advanced Material Diagnostic Technologyand College of Engineering PhysicsShenzhen Technology UniversityShenzhen 518118China

Conservation of parity plays a fundamental role in our understanding of various quantum ***,it is difficult to observe in atomic and molecular processes induced by a strong laser field due to their multiphoton character and the large number of states *** we report an effect of parity in strong-field Rydberg-state excitation(RSE)by comparing the RSE probabilities of the N_(2) molecule and its companion atom Ar,which has a similar ionization potential but opposite parity of its ground ***,we observe an oscillatory structure as a function of intensity with a period of about 50 TW∕cm^(2) in the ratio between the RSE yields of the two species,which can be reproduced by simulations using the time-dependent Schrödinger equation(TDSE).We analyze a quantum-mechanical model,which allows for interference of electrons captured in different spatial regions of the Rydberg-state wave *** the intensity-dependent RSE yield,it results in peaks with alternating heights with a spacing of 25 TW∕cm^(2) and at the same intensity for both ***,due to the opposite parities of their ground states,pronounced RSE peaks in Ar correspond to less pronounced peaks in N_(2) and vice versa,which leads to the period of 50 TW∕cm^(2) in their *** work reveals a novel parity-related interference effect in the coherent-capture picture of the RSE process in intense laser fields.

关键词： function parity Rydberg

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Extended calculations of energy levels, radiative properties, and lifetimes for phosphorus-like Se XX

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Atomic Data and Nuclear Data Tables 2025年 164卷

作者： Wang, Kai Bai, Xuan Chen, Chong Yang Yan, Jun Department of Physics and Anhui Key Laboratory of Optoelectric Materials Science and Technology Key Laboratory of Functional Molecular Solids Ministry of Education Anhui Normal University Wuhu241000 China Shanghai EBIT Lab Key Laboratory of Nuclear Physics and Ion-Beam Application Institute of Modern Physics Department of Nuclear Science and Technology Fudan University Shanghai200433 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

Highly accurate calculations are performed for the lowest 151 fine-structure levels arising from the 3s23p3, 3s3p4, 3s23p23d, 3s3p33d, 3p5 and 3s23p3d2 configurations in P-like Se XX using the multiconfiguration Dirac–Hartree–Fock and the relativistic configuration interaction methods. Complete and consistent atomic data, including excitation energies, wavelengths, E1, E2, M1, M2 line strengths, oscillator strengths, transition rates, and radiative lifetimes for these 151 levels, are provided. Our data set is compared with the NIST compiled values and other available results. The present data are accurate enough for identification and deblending of emission lines involving the n=3 levels and are also useful for modeling and diagnosing fusion plasmas. These data can be considered as a benchmark for other calculations. © 2025

关键词： Excitation energy

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An Intelligent Hexahedral Mesh Smoothing Method Based on Deep Learning

SSRN

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SSRN 2023年

作者： Liu, Lufeng Zhou, Xuan Wang, Yutao Li, Shuixiang Institute of Applied Physics and Computational Mathematics Beijing100094 China Department of Mechanics and Engineering Science College of Engineering Peking University Beijing100871 China

We introduce an intelligent mesh smoothing method for the mesh quality improvement of unstructured 3D hexahedral meshes with fixed boundaries. We apply a supervised learning framework based on the deep neural networks. We directly generate the training data from the high-quality meshes and their stochastic disturbance. The supervised learning model will build a direct mapping from the poor-quality mesh to the high-quality mesh via the training data, making it possible to overcome the complicated design of traditional smoothing methods. Using only neighboring node coordinates and constructing them in point cloud format, the trained neural network can smooth both uniform and non-uniform meshes. The intelligent mesh smoothing method generates the smoothed mesh with better mesh quality and fewer iteration steps, compared to the Laplacian method and an optimization-based method. Moreover, the trained network demonstrates high generalization capability on the mesh with different disturbance forms which are not concerned in the training data. To the best of our knowledge, this is the first time that the machine learning method has been applied to the smoothing of 3D unstructured hexahedral meshes and demonstrates good application prospect. © 2023, The Authors. All rights reserved.

关键词： Supervised learning

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Anomalous hot electron generation from two-plasmon decay instability driven by broadband laser pulses with intensity modulations 50

Anomalous hot electron generation from two-plasmon decay ins...

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50th EPS Conference on Plasma physics, EPS 2024

作者： Yao, C. Li, J. Hao, L. Yan, R. Wang, C. Lei, A. Ding, Y.-K. Zheng, J. Department of Plasma Physics and Fusion Engineering CAS Key Laboratory of Geospace Environment University of Science and Technology of China Anhui Hefei230026 China Research Center of Laser Fusion Sichuan Mianyang621900 China Shanghai Jiao Tong University Shanghai200240 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Department of Modern Mechanics University of Science and Technology of China Anhui Hefei230026 China Shanghai Institute of Laser Plasma China Academy of Engineering Physics Shanghai201800 China Joint Laboratory on High Power Laser and Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai201800 China

ISBN: (纸本)9798331305239

We have investigated the hot electron generation from TPD instability driven by broadband laser pulses with intensity modulations, which is common in the theoretical waveforms of current and future broadband laser facilities. Using a basic two-color scheme in 2D PIC simulations, our investigation has unveiled that TPD modes energy and resulting hot electron energy ratio fhot oscillate at the modulation frequency ∆ωm when ∆ωm is at the same order as the TPD growth rate γ0. If ∆ωm falls below a threshold frequency ∆ωc, such oscillation results in overall fhot anomalously exceeding the hot electron energy ratio f0 for a single-color pump. We also characterize the dependence of ∆ωc and laser plasma conditions, and we provide a scaling relation to evaluate fhot / f0 for different laser bandwidth ∆ω. © 2024 50th EPS Conference on Plasma physics, EPS 2024. All rights reserved.

关键词： Laser produced plasmas

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Dynamical Chiral Nernst Effect in Twisted Van der Waals Few Layers

arXiv

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arXiv 2024年

作者： Li, Juncheng Zhai, Dawei Xiao, Cong Yao, Wang New Cornerstone Science Laboratory Department of Physics The University of Hong Kong Hong Kong HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong Hong Kong Institute of Applied Physics and Materials Engineering University of Macau Taipa China

The Nernst effect is a fundamental thermoelectric conversion phenomenon that was deemed to be possible only in systems with magnetic field or magnetization. In this work, we propose a novel dynamical chiral Nernst effect that can appear in two-dimensional van der Waals materials with chiral structural symmetry in the absence of any magnetic degree of freedom. This unconventional effect is triggered by time variation of an out-of-plane electric field, and has an intrinsic quantum geometric origin linked to not only the intralayer center-of-mass motion but also the interlayer coherence of electronic states. We demonstrate the effect in twisted homobilayer and homotrilayer transition metal dichalcogenides, where the strong twisted interlayer coupling leads to sizable intrinsic Nernst conductivities well within the experimental capacity. This work suggests a new route for electric control of thermoelectric conversion. Copyright © 2024, The Authors. All rights reserved.

关键词： Transition metals

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An implicit unified gas-kinetic wave-particle method for radiative transport process

arXiv

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arXiv 2023年

作者： Liu, Chang Li, Weiming Wang, Yanli Song, Peng Xu, Kun Institute of Applied Physics and Computational Mathematics Beijing China HEDPS Center for Applied Physics and Technology College of Engineering Peking University Beijing China Department of Mathematics Hong Kong University of Science and Technology Hong Kong Department of Mechanical and Aerospace Engineering Hong Kong University of Science and Technology Hong Kong Beijing Computational Science Research Center Beijing100193 China

The unified gas-kinetic wave-particle method (UGKWP) has been developed for the multiscale gas, plasma, and multiphase flow transport processes for the past years. In this work, we propose an implicit unified gas-kinetic wave-particle (IUGKWP) method to remove the Courant–Friedrichs–Lewy (CFL) time step constraint. Based on the local integral solution of the radiative transfer equation (RTE), the particle transport processes are categorized into the long-λ streaming process and the short-λ streaming process comparing to a local physical characteristic time tp. In the construction of the IUGKWP method, the long-λ streaming process is tracked by the implicit Monte Carlo (IMC) method;the short-λ streaming process is evolved by solving the implicit moments equations;and the photon distribution is closed by a local integral solution of RTE. In the IUGKWP method, the multiscale flux of radiation energy and the multiscale closure of photon distribution are constructed based on the local integral solution. The IUGKWP method preserves the second-order asymptotic expansion of RTE in the optically thick regime and adapts its computational complexity to the flow regime. The numerical dissipation is well controlled, and the teleportation error is significantly reduced in the optically thick regime. The computational complexity of the IUGKWP method decreases exponentially as the Knudsen number approaches zero, and the computational efficiency is remarkably improved in the optically thick regime. The IUGKWP is formulated on a generalized unstructured mesh, and multidimensional 2D and 3D algorithms are developed. Numerical tests are presented to validate the capability of IUGKWP in capturing the multiscale photon transport process. The algorithm and code will apply in the engineering applications of inertial confinement fusion (ICF). Copyright © 2023, The Authors. All rights reserved.

关键词： Radiative transfer

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